blog: edits to package-names post.
blog: edits to package-names post.

I received a question about whether package functions named "New" were required
(they're not), so I'm adding examples of functions named "WithX" and "FromY" to
show other useful forms.

Change-Id: Iff3ddec3dca3344762f09ba52de9cd515a4bc863
Reviewed-on: https://go-review.googlesource.com/5572
Reviewed-by: Rob Pike <4dc7c9ec434ed06502767136789763ec11d2c4b7@golang.org>

gorakhargosh/blog,gorakhargosh/blog,jeffreyliguori/blog